Electronics
T2a
T2a
Fichier Détails
| Cartes-fiches | 474 |
|---|---|
| Langue | Deutsch |
| Catégorie | Electronique |
| Niveau | École primaire |
| Crée / Actualisé | 12.01.2015 / 21.01.2020 |
| Lien de web |
https://card2brain.ch/box/electronics_
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What makes the real load equalizer bus?
checks whether or not both generators run at the same RPM => In case one generator is faster than the other, coils in the speed governor ensure that the slower generator increases its RPM => the slower geni takes away real power from the faster geni
If one geni fails to be sybchronised, what happens?
If one geni fails to be sybchronised, the corresponding bus tie breaker opens automatically and the generator feeds its own AC bus
What makes a split system breaker SSB?
split system breaker divide the synchronous bus into left and right sides => the separate powering of each side of the AC system by one external power source and one APU generator ==> An external power can power one side of the AC while an APU generator powers the other side
=>can be operated manually only on ground => SSB closed = both side of the synchronous bus are connected
NBPT: No Break Power Transfer
No Break Power Transfer => when power source switching a loss of power about 1/10 sec => to prevent this NBPT=> the two different power sources are first synchronized, once the synchronization process is completed, the old power source is witched off
What means Variable Frequency VF?
VF implies that paralleling of power is not possible any more => the resistive loads are directly driven via primary power distribution from each generator bus whereas small loads being fed by distributed secondary power distribution secondary power distribution
=> Frequency and volatge correction may take place directly at the loads
VF is an xy system and that means?
Variable Frequency is a isolated system => each generator has its own loads. There is no parallel feed. The loads are supplied directly from the generator, without constant frequency
What is the only possibility providing high electrical power on a common bus when using VF generators ?
High DC voltage => the use of large consumers requires an increase of voltage in order to keep diapers for cabling small (less current for the same power => higher voltage)
VF führt zu more electrical aircraft => improve reliability and reduction of fuel, why?
a replacement of pneumatic bleed air systems and hydraulic pumps by z.B. electrical pumps etc.
Three possibilities of disconnections (electrical system) are feasible:
1. bus tie breaker
2. generator breaker
3. the field relay of the generator
The operating principle of a fuse is...
A wire with a pre-determined melting point.
Fuses are rated to a value by ...
the number of amperes they will carry
A non trip-free circuit breaker that has tripped due to overload...
can be re-made, but should not be held in
A thermal circuit breaker works on the principle of...
differential expansion rates of different metals
A current limiter fuse in a DC generation system is used to...
allow a short term overload before rupturing (brechen)
A magnetic circuit breaker...
is a quick tripping response protective system
Circuit breakers are fitted in...
A proximity switch works on principle of...
magnetic attraction
A relay is...
Heaters and electrical de-icing systems can be supplied by frequency-wild AC with voltage regulation because...
Field excitation of an AC generator when running is provided (bereitgestellt)by...
The output power of a constant frequency AC system is expressed in terms of...
In an aircraft electrical system where AC generators are not paralleled mounted, the changeover relay allows
An air-driven generator (RAT) supplies...
What happens to the current in a series capacitive circuit when frequency increases?
increases
The generator of the auxiliary power unit (APU) can only be used when
On starting, in a brushless AC generator with no commutator rings, the generator is activated by...
a set of permanent magnets.
Regarding synchronous motors, what is the relationship between RPM, frequency of the applied voltage and number of pole pairs ?
The induction motor has...
To ensure correct load sharing between AC generators operating in parallel:
The rating of an AC generator is usually given in...
kVA = kilo Vatt
Full wave rectification of a single phase AC supply requires an arrangement of:
4 diodes
The advantage of a "unipole" system is:
(i) lighter
(ii) easier fault finding
(iii) more likely to short circuit
(iv) less likely to short circuit
(v) it is not a single wire system
1 2 4
Transformer changes ? and he has?
Transformer changes voltage and he has primary and secondary windings
In aeroplanes of metal construction, the structure itself ...
An earth return electrical system has:
When a generator is on line and its associated ammeter reads 10 amps, this is an indication of...
generator load
How are the loads on an aircraft busbar connected?
in parallel so that current reduces through the busbar as loads are switched off
What is the result when current passes through a rectifier?
The purpose of bonding is to...
A transformer is a device for:
